(1) Field of the Invention
The present invention relates to a method and an apparatus for joining an adhesive tape to a back face of a semiconductor wafer after working the back face of the semiconductor wafer.
(2) Description of the Related Art
Generally, a surface protective tape is preliminarily joined to a surface of a semiconductor wafer (hereinafter, simply referred to as a wafer) which has been subjected to a pattern forming process, and part of the surface protective tape, which protrudes from an outer circumference of the wafer is cut out along an outer peripheral edge of the wafer. The wafer whose whole surface is protected with the surface protective tape is turned upside down, a process of polishing a back face of the wafer is performed on the back face of the wafer, which faces upward, and the wafer is turned back by a wafer transport unit and housed into a wafer cassette with the wafer pattern surface directed upward. After that, the wafer to which the wafer back face polishing process has been completed is integrated with a ring frame by joining an adhesive tape for dicing to the back face of the wafer for a so-called dicing process of dicing the wafer into chips. The posture of the wafer when the adhesive tape for dicing is joined to the back face of the wafer is that, typically, the back face of the wafer is directed upward (see, for example, JP-A 10-189693 (1998)). At the time of wafer mounting of integrating a wafer and a ring frame, the wafer housed in the wafer cassette is turned upside down.
In JP-A 10-189693 (1998), a wafer is turned upside down on the outside of the adhesive tape joining apparatus and mounted with the wafer back face directed upward on a wafer holding table. An adhesive tape is joined to the wafer, and the wafer and the ring frame are integrated with each other. In short, the back face of the wafer is directed upward and the adhesive tape is joined to the back face from above, thereby integrating the wafer and the ring frame.
Those works are done in a clean room and it is necessary to effectively use the limited space of the clean room. Consequently, for example, in order to automate mounting of a wafer onto a wafer holding member, joining of an adhesive tape, and the like, a wafer turning mechanism has to be mounted on the apparatus disclosed in JP-A 10-189693 (1998). When the wafer turning mechanism or the like is added as an additional function, the size of the apparatus accordingly increases and it becomes difficult to effectively use the limited space of the clean room.
The rigidity of a wafer subjected to back face grinding decreases and, due to the influence of the pattern surface, a warp occurs. Due to the warp, holding of the wafer at the time of transport becomes unstable and problems such that the wafer drops during a wafer turning work and the wafer cannot be transported and held with high precision occur.